This invention relates to the field of orthopedic implant devices. A typical application is as an intramedullary fixation assembly used for the fixation of bones and the correction of deformities in the foot.
Orthopedic implant devices such as intramedullary nails, plates, rods and screws are often used to repair or reconstruct bones and joints affected by deformity and disease such as Charcot arthopathy caused by diabetes in some patients. Charcot arthopathy (or Charcot foot) is a destructive process affecting many regions including joints of the foot and ankle in diabetics. Charcot arthopathy can affect any joint in the body but is often seen in the foot. In the foot, the Charcot process typically affects the tarsal and metatarsal bones and the tarsometatarsal and intertarsal joints which causes the foot to lose its arch. This causes fragmentation, dislocation and fractures that eventually progress to deformity, instability and bony prominences. Foot ulcers may develop which often lead to deep infection and sometimes amputation.
FIG. 1 depicts a human foot 100 afflicted with Charcot arthopathy. Phalanges 110, the first metatarsal 120, medial cuneiform 130, navicular 140, and talus 150 bones are depicted in foot 100. The deformity in the foot will be apparent.
Early treatment for Charcot foot includes the use of therapeutic footwear, immobilization of the foot, and/or non-weightbearing treatment. Surgical treatments include orthopedic fixation devices that fixate the bones in order to fuse them into a stable mass. These orthopedic implant devices realign bone segments and hold them together in compression until healing occurs, resulting in a stable mass.
Infection and complications are a major concern in these procedures. Wound closure is technically demanding for the surgeon, and devices that add surface prominence such as plates or exposed screws, add to the difficulty by requiring greater tissue tension during incision reapproximation. This increases the risk of post-operative wound infections and dehiscence that may ultimately result in limb amputation.
There is therefore a need for improvements in intramedullary fixation assembly and methods of use that overcome some or all of the previously described drawbacks of prior art fixation assemblies and processes.